Cooling system



Oct.r13, 1936. c. s. LEOPOLD COOLING SYSTEM Filed April 18, 1953 3Sheets-Sheet 1 5 sheets-sheet 2 C. S; LEOPOLD COOLING SYSTEM Filed April18, 1933 Oct. 13, 1936.

oct- 13, 1936- c. s. LEOPOLD 2,056,970

COOLING SYSTEM Filed April 18, 1953 3 Sheets-Sheet 3 Patented Oct. 13,193.6'

UNITED vSTATES PATENT OFFICE oooLrNG SYSTEM Charles S. Leopold, ElkinsPark, Pa. Application April is, 193s, serial Np. 666,668 11 claims. (cl.ca -141) This invention relates to a cooling system and moreparticularly to an arrangement of such system whereby an economy of sizeand capacity of apparatus is effected.

In refrigerating systems comprising evaporators, compressors andcondensers, it is the usual practice to design the equipment to meet thepeak demand with the result that the system is usually .operated at muchless thanv full load.

This, for example, is particularly true in systems designed for coolingof air in theatres, office buildings, or the like, which are in use onlya relatively small part of an entire day and seldom at peak capacity.

As a result of this usual type of' design there results a decrease inoperating efficiency and since the apparatus .must be sufficient to meetthe simultaneous peaks, the rst cost is therefore high. Whererefrigeration is applied to air conditioning systems it is customary todesign the refrigerating apparatus to meet the simultaneous peaks due tomaximum outside temperature and humidity, maximum heat losses from theconditioned space, and maximum heat due to the sensible and latent heatgiven oi by the occupants of the conditioned space. This cornbined peakis greatly in excess of the average load with the consequent losses justmentioned.

Tanks to store cold water during oi peak periods have at times been usedto carry the high loads of the peak but their use has not provedgenerally satisfactory due to the excessive size of the containers whichare required. More recently evaporator coils have been immersed in atank of Water and ice allowed to accumulate during the off peak periodsto be used to take care of the peaks. Due to the high latent heat offusion of ice this resulted in the use of smaller tanks and partiallysolved the problem. It oiiered, however, the serious objection that atcertain rates of ow of waterV through such a tank it is diicult to bringthe Water to a temperature close to that of the ice. The exchange ofheat -from ice to water depends upon the' velocity of the water and in asystem as above described even though the water is caused to passthrough a long channel to contact with the ice the velocity is very lowas the channels must be wide enough so that the ice will not freeze themshut when there is a maximum amount of ice on the coils.

Furthermore, when the ice is melting from the coils the water channelsWiden with a consequent decrease in velocity and in heat transmission.

There is an additional disadvantage in that the ice formation is notopen to inspection and that if a refrigerating system fully automatic inoperation is used it is difficult to use a control to shut off themachine when a satisfactory amount of ice is formed. 5

It is the broad object of this invention to provide a system for thestorage, control,` and melting of the ice which will eliminate orsubstantially reduce the aforementioned objections.

` Specifically the invention is concerned with the 10 formation of iceon cooling surfaces over extended periods followed by the melting of theice by water flowing in a lm thereover during the hours of use of thecooling effect so that the supply of cooling effect can vary to meet theactual l5 demand whereas the evaporation of the refrigerant proceeds ata substantially constant rate, except as indirectly effected by thethickness of ice formation on the coils. Additionally in the preferredembodiment of the invention the ice is 20 formed on surfaces cooledbelow the freezing point of water by the flow over such surfaces of afilm of water during the off peak periods. With this arrangement thefllm oW serves at certain periods for the building up of ice and atother 25 periods for its melting'to cool the flowing water.

Subsidiary objects of the invention particularly relating to the controlof ice building upon refrigerating surfaces and other details ofconstruction involving, for example, controls. of 30 pumps and therefrigerating apparatus, will be apparent from the following descriptionread in conjunction with the accompanying drawings in. which:

Fig. 1 is a diagrammatic view of a preferred 35 embodiment of theinvention, certain of the parts being shown broken away to show interiorconstructions;

Fig. 2 is a vertical section through theice containing chamber; 40 Fig.3 is a diagrammatic View similar to Fig. 1

but showing an alternative arrangement;

Figs. 4 and 5 are likewise similar diagrammatic showings of furthermodifications; and

Fig. 6 is a diagrammatic view showing a modi- 45 cation in which the iceis formed in a different fashion although cooling by the ice is effectedin accordancewith the invention.

Referring rst to Figs. 1 and 2 there is illustrated at 2 a heatinsulated chamber in the base 50 of which there is provided an open tank4 for the reception of water. As will be obvious hereafter this tank 4need not necessarily form a part of the chamber 2 but may be arranged toreceive water therefrom either by gravityilow or by the 55 use of anauxiliary pump. Located in the upper portion of the chamber 2 arerefrigerating coils 6 in which refrigerant is evaporated in the usualfashion to reduce their temperature below the freezing point of theliquid used in the system which willbe described herein as wateralthough it will be understood that other liquids such as aqueoussolutions, or even non-aqueous liquids, may be used in accordance withthev invention for various purposes. The coils 6 form a part of aconventional refrigerating system including a suitable compressor andcondenser. It is on the outside of these coils that ice is built up asindicated at 8 preferably in the fashion indicated in the drawings so asto completely imbed the coils in off peak periods as will be obvioushereafter.

.A conduit III joins the lower pa'rt of the tank 4 with the inlet of awater pump I2, the outlet of which is connected to a conduit I4 in whichthere is interposed an upwardly opening check valve I6 and a restrictedorifice I8. Water is delivered by the conduit to a system of spraynozzles indicated at 20 located above the coils 6 and designed to spraywater thereon so that it will flow over the coils in heat exchangerelationship therewith either by direct contact with the metallic coilsor, as partial freezing takes place, over the ice built up thereon withthe result that either more ice is formed or, if the Water is warm, acertain amount is melted.

A float 22 located in the tank 4 controls a switch 24 which is arrangedto open the circuit energizing the motor I2 when the float drops to acertain position corresponding to the minimum height of liquid in thetank. An overflow 3U is arranged to prevent the liquid from rising toohigh, as in a dehumidiifying system the moisture taken from theatmosphere is continually added to the total water in the system.

On the pump side of the orifice I8 there communicates with the conduitI4 a tube 26 connected to a pressure controlled switch 28 which controlsthe circuit of the refrigerant compressor in the refrigerating system.This ,arrangement is such that as long as the pump I2 is operating, byreason of the restricted orifice there will be a pressure on the pumpside thereof suiiicient tor maintain the switch 28 closed and thecompressor running. When the flow through I4 ceases this pressure is nolonger maintained and the switch 28 is automatically opened stopping thecompressor.

This arrangement provides safety for the compressor since it insuresthat the compressor will not operate when there isno water passing overthe coils from which heat may be absorbed.

Water is drawn from the tank 4 through a pipe 32 and an outwardlyopening check valve 33 into one port of a three-way valve 34. This valveis such that, depending upon its operation, the water'will be receivedfrom the pipe 32 or alternatively from the pipe 40 and delivered throughthe connection 36 to a; pump 38 by which it will be delivered in theform of a spray into a chamber 42 through the pipe 44 and spray nozzles46. The spray produced in the chamber 42 is traversed by air iiowing toa blower 48 and discharged thereby through a conduit 50 to the point ofuse. While there is.illustrated specifically in this modication an airconditioning apparatus it will be obvious that the invention isapplicable to cooling systems in general in which cooled water or otherliquid is passed in heat exchange relationship with a warmer medium toabstract heat therefrom. It happens that the system is particularlyuseful in connection with air conditioning apparatus in view of the factthat this involves the imposition of various loads and consequentlyutilizes the advantageous features of the system.

'I'he three-way valve 34 which may be of conventional type actuated byfluid, the flow of which under pressure is controlled by a thermostat orother 'sensitive instrument, is arranged to be operated by a thermostatlocated, for example, either in the water accumulating from the spray inchamber 42 or the air after passing through the water spray. Its controlis such that if the temperature at the thermostat is high it willprovide communication between 32 and 36 shutting olf the line 40. On theother hand, if the temperature at the thermostat is low it will shut offthe connection 32 and open communication between 40 and 36 with theresult that a circulation of liquid will be maintained without cooling.In general, it is desirable that the three-way valve be capable ofassuming intermediate positions so that the flow may be apportioned,part of thev liquid passing to the pump 38 being received from 32 andthe remainder from 40, the proportions depending upon the demandindicated by the thermostat.

A pipe 52 whose open end within the chamber 42 is located at a levelhigher than the open end of the pipe 4U provides for the flow of liquidfrom chamber 42 to nozzles 54 located adjacent the nozzles 20 and alsoarranged to discharge water upon the coil 6.

The apparatus so far described will incorporate not only the elementsalready mentioned but also manually operated valves and switchesdesirable for use in shutting down and re-starting. The arrangement ofthese,` however, depends on the convenience of the operator of theinstallation and are not described since they form no essential part ofthe automatic system. The operation of the system may be described asfollows:

Assuming a peak load, in which case the valve 34 would providecommunication between 32 and 36 and close off 40, liquid would be drawnfrom the tank 4 and sprayed into 42, thus cooling the air, and wouldthen return through the pipe 52 and nozzles 54 over the coils 6 by whichit would be-,cooled whence it would drop again into the tank 4. If theconditions were such that dehumidifying was taking place there would beno necessity for adding further water. In fact, eventually the amountmight increase so that overow through would take place. If evaporationoccurred Water would be added to the tank 4 either automatically or atintervals by manual operation. At the same time during such peak loadsfurther cooling would be eiected by the flow of water caused by the pumpI2 with the resulting additional spray through the nozzles 20. By reasonof the ow through the orifice I8 the pressure in 28 would be maintainedand the refrigerating apparatus kept operating. The' iioat 22 would ofcourse be'raised with the result that the -pump I2 would continue toproduce such How.

If now a decreased demand on the apparatus was made, evidenced by alowered temperature of the water collecting in the bottom of chamber 42,the valve 34 Would be operated to decrease or even cut off the flowthrough 32 and permit flow through 40. In such case a recirculation ofthe spray from the nozzles 46 would occur Without addition of cool waterthrough 32 until the circulated water temperature would rise. Under verylow demands such as might occur, for example, in olf hours, or if theexternal temperature was low so that the water spray would be used forair washing alone, no flow through 32 would take place. At the sametime, by reason of the free flow through 4I! the level in the bottom of42 would drop so that no water would pass through the nozzles 54. Underthese conditions the pump I2 would continue to operate to circulatecoldA water from the tank 4 through the nozzles 28 and over therefrigerating coils 6. i As the temperature would continue to fall icewould build up upon the coils. As the formation of ice continued theamount of liquid in the circulating system would decrease andconsequently the liquid level in the tank 4 would drop. Eventually itwould drop to su'ch extent that the float 22 would open the switch 24stopping the pump I2 and, by reason of the occasioned drop of pressureat 28, also the refrigerant compressor. The function of the float 22will now be obvious. It is so arranged that it will interrupt furthercirculation of water when the liquid level in the tank drops to anextent corresponding to the maximum desired coating of ice upon thecoils 6. In this way the thickness of the ice coating is definitelylimited and there is definite insurance against the closing off of thepassages between the coils by a solid cake of ice.

If the demand on the system is then increased, the valve 34 will againopen the passage 32 and Warm water will be sprayed from the nozzles 54upon the ice. This Water flowing in a film over the ice will graduallymelt the same acquiring a temperature approximately that of thefreezing,

point of the liquid. In this fashion the amount of liquid in the tank 4again increases with a consequent rise of the float 22 closing theswitch 24 and restarting pump I2 and the refrigerant compressor.

In view of the accumulation of the ice upon the coil in oif peak periodsit will be obvious that the refrigerating apparatus need only bedesigned for a little more than the average twenty-four hour demandrather than for the large peaks of short duration as might occur, forexample, at mid-day in a restaurant or the like. By reason of the highlatent heat of fusion of water there will in general, except when longextended peaks occur, be ice upon the coils 6. This by its gradualfusion reinforces the refrgerating action of the coils 6 during peakperiods. There is thus, in general, an equilibrium condition reached atany time either resulting in a slow building up or slow melting down ofthe ice on the coils 6. The refrigerating apparatus of small size maythus run at its maximum eiliciency over extended periods and take carenot only of peak loads but also of periods of low or no demand duringwhich it will prepare the apparatus for peaks.

Referring now to Fig. 3 there is illustrated therein a modifiedarrangement resembling rather closely that of Fig. 1. In this case allthe parts are the same with the exception of the return to the chamber 2from the chamber 42 wherein heat exchange takes place. The conduit 56 inthis case is connected at 58 to the conduit I4 so that the returnedliquid is sprayed through the nozzles 20 as well as the liquid passingfrom the pump I2. In this case it is only necessary that the head inpipe 56 be sufficient to insure that the flow will be downwardly andthrough'the nozzles 20 rather than in a reverse direction. The orificeI8` of course assures a relatively low pressure-at 58 due to the pumpI2, so that the desiredequilibrium condition is readily attained. 'I'heoperation is which the conduit I4 communicates with one branch of a T68. Another branch of this T communicates with a pipe 62 leading to aheat exchange device indicated conventionally at 64 which may, asbefore, be an air conditioning arrangement, but may be of 'any typewherein cooling is to be eifected. The liquid from the exchanger 64returns through pipe 66 to a threeway valve 68, one opening of which hascommul nication through connection 10 with the third branch of the T 60.'I'he other port of the threeway valve communicates through 12 with thenozzles 20.

In this arrangement the valve 68 may be thermostatically controlled, inthis case so as to cause a flow through I4, 62, 64, 66 and 12 duringpeak loads and through I4, 68, 10 and 12 during periods of no demand,the flow through the heat exchanger at the latter time being completelyinterrupted 'by' closure of the outlet of the conduit 66. Forintermediate demands, the flow is apportioned by intermediate conditionsof the valve 68. In this apparatus the pump I2 functions not only to pro.fide the recirculation in the refrigerating chamber but also to supplythe flow to the heat exchanger. The operation of building up and meltingdownthe ice is substantially that heretofore described.

Fig. 5 represents a further development along the lines of Fig. 4 butembodying a recirculation through the heat exchanger in addition to thatthrough the refrigerating apparatus. In this case the connection I8between the tank 4 and the pump I2 contains an outwardly opening checkvalve 14. The conduit I4 connects with one branch of a T 16. Anotherbranch of this T communicates through 18 with the heat exchanger 88 fromwhich discharge takes place through 82 to one branch of a three-wayvalve 84. Another branch of this valve is connected by 86 to the thirdbranch of the T 16. The third branch of the three-way valve 84 connectsthrough 88 with The valve 14 and the pump I2 through a pipe 84 in whichis interposed a thermostatically controlled valve 96.- The valve 84 iscontrolled in the same fashion as the valve 68 of Fig. 4 and correspondsthereto, valves 84 and 96 apportioning the flow by their partialclosures of the respective conduits. The valve 96 is thenthermostatically controlled by the temperature in the space to be cooledor by a thermostat, say in the pipe 18, with the result that it wilipermit a circulated flow of partially warmed water so; that the waterentering the pump is made up of cooled water from the tank 4 as well asa certain amount of this partially warmed water. When heat transfer isnot required in 88, valve 84 stops circulation through the heatexchanger80 and valve 86 is closed s0 that the building up of ice on the coilstakes place until the operation is automatically stopped when suilicienthas been built up by thefall of liquid level in the tank 4.

In Fig. 6 there is illustrated another embodiment of the invention inwhich, however, the building up of ice upon the coils 6 does not takeplace entirely by the flow of `a lm thereover. In this modification thecoils 6 are immersed in a tank |00. At the bottom of this tankcommunication is furnished through |02 to a tank |08, the passage beingcontrolled in the present instance by a hand operated valve |04- which,as will be pointed out later, may be automatic. An overflow |06 extendsfrom the upper end of tank |00.

and connects with |02.

y At the bottom of the tank |08 an outlet pipe |0 communicates throughan outwardly opening check valve |2 with one branch of athermostatically controlled three-way valve ||4 corresponding to thevalve 34 of the modification of Fig. 1. Another branch of this valvecommunicates with a pump |6 which delivers Water to the heat exchanger|20 through a pipe |22 connected with nozzles |24. A bypass connection|28 in which is interposed a shut-off valve |26 connects 22 with thepipe |30 which delivers water to the nozzles 20. A pipe |32 connects thechamber |20 with the pipe |30 being equivalent to the pipe 56 of Fig.'3.This pipe |32 opens in the chamber |20 above the level of the pipe ||8which is connected to the third branch of the valve ||4.

A thermostat |34 extends through the side wall of the chamber |00 insuch position that ice forming on the coils 6 will surround it. It isadjusted so as to interrupt the operation of the refrigerating mechanismproviding refrigerant for the coils 6. In this manner the thickness ofthe rice obtained is limited.

When the apparatus of Fig. 6 is in its idle condition the chamber 00contains water so that the coils 6 therein are submerged, the valve |04at this time being closed. The refrigerating apparatus is then operatedto bring. the coils 6 below the freezing point whereupon ice begins tobuild up on them until the operation is interrupted by the thermostat|34 which is adjusted so as to stop the refrigerant compressor when itiscovered to a predetermined extent by the ice which in its interiorwill have a temperaturebelow the freezing point. When this condition isattained the valve it may alternatively be automatically opened also bythe operation of thermostat. .The remaining liquid in |00 is thusdischarged into the chamber |08.

When cooling in |20 is desired the valve ||4 Will open ||8 or ||0, orboth, as the conditions may warrant and valve |26 may be closed orpartly opened so as to apportion the flow and obtain lthe desiredcooling action by the flow of the liquid in the form of a film over theice within the previouslydescribed. Its'advantage lies in thefact thatthe circulating'pump need not be used during the ice formation, forexample, overnight, although ice may be formed during off peak periodsat certain times by the flow of liquid over the pipes 6 as heretoforedescribed.

It will be seen that the various arrangements indicated above provide asulciently rapid circulation of water to obtain an excellent heattransfer so thatV the water supply either in the tank 4 of the firstmodifications or the tank |08 of the modification of Fig. 6 may bemaintained very close to the temperature of the ice. This is essentialin. air conditioning systems where low dewpoints are required.

While more power is required to produce a |04 may be manually openedalthough medium. and returning it to the system.

given refrigerating effect at 32 than at higher temperatures, and thepresent system may thus require more power per ton of refrigeratingeffect this is more than offset by the great decrease in size of theapparatus and the lower cost of electrical energy for the supply ofsmaller peaks andv use over longer periods.

It will be noted that the invention embodied in this application isapplicable to the system described and claimed in my application, SerialNo. 658,370, led February 24, 1933.

It will be clear that various changes may be made in the embodiments ofthe invention without departing from the scope thereof as defined in thefollowing claims.

What I claim and desire to protect by Letters Patent is:

1. In combination, means for holding a supply of liquid, means providinga surface cooled below the freezing point of the liquid, -means forproducing a ow of liquid from the supply in heat interchange with saidsurface'in the form of a lm, and back to the supply, whereby there isbuilt up on said surface a coating of frozen liquid over which theliquid film flows, and means for interrupting said flow when the liquidin the supply decreases below a predetermined amount, whereby thethickness of coating is limited.

2. In combination, means for holding a supply of liquid, means providinga surface cooled below the freezing point of the liquid, means forproducing a flow of liquid from the supply in heat interchange with saidsurface in the form of a film, and backv to the supply, whereby there isbuilt up on said surface a coating of frozen liquid over which theliquid lm flows, means for interrupting said fiow when the liquid in thesupply decreases below a predetermined amount, Wlfiere-A by thethickness of coating is limited, and means for restarting said flow whenthe liquid in the supply again increases.

3. In combination, means providing a surface cooled below the freezingpoint of a liquid, means l the thickness of the coating attains apredetermined amount, and means for interrupting at the same timefurther cooling of said surface. 4. In combination, means providing asurface cooled below the freezing point-ofa liquid, means forrecirculating the liquid in the form of a fllm in heat interchange withsaid surface wherebyA there is built up on said surface a coating offrozen liquid over which the liquid film ows..

means for interrupting said recirculation when the thickness of thecoating attains a predetermined amount, means for interrupting at thesame time further cooling of said surface, and means for simultaneouslyresuming the recirculation and further cooling of the surface when thethickness ofthe coating decreases.

5. In combination, a circulatory system includving means providing asurface cooled below the freezing point of a liquid and means forrecircuv abstracting cooled liquid from said system, passing it in heatinterchange with another warmer 6. In combination, a circulatory systemlncluding means providing a surface cooled below the freezing point of aliquid and means for recirculating the liquid in the form of a lm inheat interchange with said surface whereby there is built up on saidsurface a coating of frozen liquid over which theliquid film iows, asecond circulatory system including means for producing a flow of liquidand means whereby the liquid is brought into heat interchange withanother warmer medium, and means whereby cooled liquid may pass from theiirst system to the second and warmer liquid may return from the secondto the first.

'7. In combination, a circulatory system including means providing asurface cooled below the freezing point of a liquid and means for re-`circulating the liquid in the form of a film in heat interchange withsaid surface whereby there is built up on said surface a coating offrozen liquid over which the liquid film ows, a second circulatorysystem including means for producing a flow of liquid and means wherebythe liquid is brought into heat interchange with another warmer medium,and automatically controlled means whereby cooled liquid may pass fromthe first system to the second and warmer liquid may return from thesecond to the first.

8. In combination in a water cooling device, a conduit, a pump forproducing a flow of water through the conduit, fixed ilow restrictingmeans in the conduit, and a pressure controlled device communicatingwith the conduit on the pump side of the iiow restricting means wherebythe pressure on said pressure-controlled device depends upon the rate offlow of water through the conduit.

9. In combination, means providing a series of surfaces cooled below thefreezing point of a liquid, means for recirculating the liquid in theform of a lm in heat interchange with and between said surfaces wherebythere are built up on said surfaces spaced coatings of frozen liquidbetween and over which the liquid flows in the form of a lm, and meanswhereby the thicknesses of the coatings are limited to avoid closing ofthe passages between the coatings.

10. In combination, means providing a series of surfaces cooled belowthe freezing point of a liquid, means for contacting liquid with saidsurfaces whereby there are built up on said surfaces spaced coatings offrozen liquid, and for recirculating liquid in the form of a lm betweenand over said coatings, and means for limiting the thicknesses of thecoatings to avoid closing of the passages between the coatings.

11. In combination, means providing a series of surfaces cooled belowthe freezing point of a liquid, means for contacting liquid with saidsurfaces whereby there are built up on said surfaces spaced coatings offrozen liquid, and means for limiting the thicknesses of the coatings toavoid closing of the passages between the coatings, whereby the passagesare open for the pasand over said coatings.

sage Vof fluid between CHARLES S. LEOPOLD.

